Method of assembling electromagnetic high-current-carrying capacity vacuum relay



Aug. 22, 1967 J. s. HAWKINS 3,336,664

METHOD OF ASSEMBLING ELECTROMAGNETIC HIGHCURRENT-CARRYING CAPACITYVACUUM RELAY Original Filed Oct. 15, 1962 5 Sheets-Sheet 1 INVENTOR JACKS. HAWKINS Aug. 22, 1967 J, l s 3,336,664

METHOD OF ASSEMBLING ELECTROMAGNETIC HIGH-CURRENTCARRYING CAPACITYVACUUM RELAY Original Filed Oct. 15. 1962 5 Sheets-Sheet 2 INVENTOR.

E JACK s. HAWKINS g- 22, 1967 J. s. HAWKINS METHOD OF ASSEMBLINGELECTROMAGNETIC HIGH'GURRENTCARRYING CAPACITY VACUUM RELAY 3Sheets-Sheet Original Filed Oct. 15, 1962 INVENTOR.

JACK S. HAWKINS United States Patent METHOD 0F ASSEMBLINGELECTROMAGNETIC This is a division of application Ser. No. 230,343,filed Oct. 15, 1962 (now Patent No. 3,200,222). This invention relatesto transfer relays, and particularly to an electromagnetically operatedmultiple-contact relay of the parallel leaf spring type.

High current electromagnetically operated transfer relays have in thepast been plagued by the inability to withstand impact shock andvibration characteristics 1mposed by contemporary environments such asjet planes and missiles. It is therefore one of the principal objects ofthe present invention to provide a high-current-carrying transfer relayhaving a multiple-contact configuration capable of withstandingvibration up to about GS at about one thousand cycles per second.

Reliability of a relay has been another quality demanded by militaryapplications in which failure of a relay because of its inability tocarry high electric currents could be disastrous. It is thereforeanother object of the present invention to provide a transfer relaydesigned to carry continuously at least 200 amps of direct currentwithout harmful effects due to the generation of heat by the passage ofsuch large amounts of current. 1

Another factor important in determining whether a transfer relaypossesses the requisite reliability for use in systems which do notpermit of failure is the necessity of various difiicult-to-achieveadjustments to provide proper gap spacing and voltage standoff betweencontacts during operation, and the necessity of additional adjustmentsrequired to be made after the unit is assembled so as to maintain therelay in operation. Accordingly, it is a still further object of thepresent invention to provide a transfer relay in which all ad ustmentsare made during fabrication and in which no adjustments are necessaryafter the unit is sealed.

Although reliability of the unit is an extremely important factor indetermining whether a relay is suitable in a particular environment,another important factor is the cost of the unit. Cost is oftendetermined by the complexity of the design and a requirement for skilledlabor in fabricating the parts and assembling the unlt. It is thereforea still further object of the present invention to provide anelectromagnetically operated highcurrent-carrying transfer relay inwhich the indiv1dual parts can be mass produced and assembled byrelatively unskilled labor, thus reducing the initial cost of the relaIt has been found that one way in which high-currentcarryingcapabilities is achieved is to separate the phases in a three-phasecircuit and interrupt each phase separately. It is accordingly anotherobject of the invention to provide a three-phase high-current-carryingtransfer rela at the high currents at which the relay of this inventionis designed to operate, one of the problems required to be solved is theisolation of each phase from the other phases in the three-phase relay.It is therefore another object of the invention to provide adequatephase shielding between the three phases of the relay.

A still further object of the invention is the provision of a transferrelay in which different configurations such as single-polesingle-throw, or single-pole double-throw, or three-pole single-throwmay be arranged simply and effectively using many of the same partscommon to all configurations and utilizing the same methods of assembly.

Still another object of the invention is the provision of a novel methodof assembling a transfer relay so that the contact parts after assemblyand final seal are in finally adjusted position and require no furtheradjustment after the unit is sealed.

Still another object of the invention is the provision of anhermetically-sealed envelope for a high-currentcarrying transfer relayin which shield means are provided to prevent formation of a conductivecoating of vaporized contact metal on the inner non-conducting surfacesof the envelope.

The invention possesses other objects and features of advantage, some ofwhich, with the foregoing, will be apparent from the followingdescription and the drawings. It is to be understood however that theinvention is not limited to the showing made by the said description andthe drawings, as it may be incorporated in various forms within thescope of the appended claims.

Broadly considered, the transfer relay of the invention comprises agenerally cylindrical hermetically sealed envelope fabricated from amultiplicity of stacked and alternately arranged dielectric and metalparts hermetically brazed one to the other, and having appropriatelyinterposed therealong a multiplicity of radially extending terminalplates or contact flanges of heavy cross-section and having a portionprojecting outside the envelope as thermal radiating elements, and aportion extending into the envelope to provide a solid andvibration-free support for the current-carrying contact as sembly. Eachof the annular contact flanges supports adjacent its inner periphery aheavy tungsten contact extending in a direction parallel to the axis ofthe envelope and having an appropriate contacting surface adapted to beengaged by a movable or floating contact plate suitably supported on theenvelope and actuated by a central actuating stem. Each of the movablecontacts includes a metallic ring, preferably of molybdenum, having aradially extending resilient finger extending past the central axis ofthe envelope and having brazed on the free end thereof a heavy floatingcontact plate or shorting bar adapted to short circuit spaced and fixedcontact points within the envelope. The actuating stem is supported on afloating armature adapted to be energized by a suitable solenoidassembly hermetically closing one end of the envelope. In one aspect ofthe invention the relay is adapted to separately interrupt the phases ofa three-phase circuit so as to prevent interference between the phaseswhen a circuit is broken therethrough. Each phase is provided with apair of contacts isolated within a separate contact chamber fromadjacent contacts. In another aspect of the invention the relaycomprises a single-pole double-throw relay utilizing a common contactflange isolating the two switches.

Referring to the drawings:

FIG. 1 is a vertical cross-sectional view of a three-phase relay, theplane of section being indicated by the line 1-1 in FIG. 4.

FIG. 2 is a vertical cross-sectional view taken in the plane indicatedby the line 2-2 in FIG. 4.

FIG. 3 is a horizontal cross-sectional view taken in the plane indicatedby the line 3-3 in FIG. 1.

FIG. 4 is a plan view of the embodiment illustrated in FIG. 1.

FIG. 5 is a vertical cross-sectional view of a different embodiment ofthe invention in a single-pole double-throw relay.

FIG. 6 is a fragmentary cross-sectional view taken through a portion ofthe wall as indicated by the line 6-6 in FIG. 5.

FIGS. 1, 2 and are shown twice actual size, FIGS. 3 and 4 are shownactual size, and FIG. 6 is shown four times actual size for clarity.

In terms of greater detail, the transfer relay in the embodimentdisclosed in FIGS. 1, 2, 3 and 4 comprises an hermetically sealedgenerally cylindrical envelope portion designated generally by thenumber 2, closed at one end by a solenoid assembly 3 and at the otherend closed by a domed end cap assembly 4.

The electromagnetic solenoid assembly comprises a generally tubularhousing portion 5 having a coaxially arranged core member 6 thereinsupported on the housing 5 by an integral and transversely extendinghermetic wall 7. The wall is spaced intermediate opposite ends of thehousing, the inner end portion 8 of the housing being provided with aradially extending seal flange 9. The other end of the housing isprovided with a detachable closure plate 12 secured to the open end ofthe housing by a suitable screw or bolt 13, the closure plate serving toenclose a magnetic coil 14 within the housing and complete the magneticcircuit around this end of the housing. A radially extending flange 16is provided brazed about the outer periphery of the housing to serve asa mounting means for the relay. An armature 17 is provided adjacent theinner end 8 of the housing and is adapted to move axially toward andaway from the housing upon energiza tion and de-energization of thesolenoid. Suitable spring means 18 are interposed between the wall 7 andthe armature.

In FIGS. 1, 2 and 5, the armature is shown in coreenergized position.Inasmuch as similar electromagnetic solenoid means are utilized for theseparate embodiments illustrated in FIGS. 1 and 5, corresponding partshave been indicated by corresponding reference numbers. In bothembodiments axial movement of the armature is restricted in onedirection by the inner end 8 of the housing, and in the other directionby a radially extending flange 19 formed on one end of a cylindricalmetallic shell portion 21, the other end of which is provided with anintegral and radially outwardly extending flange portion 22 abuttingagainst and having its outer peripheral edge coincident with the outerperipheral edge of sealing flange 9.

The coincident edges of flanges 22 and 9 are adapted to be hermeticallyand integrally united as by heliarc welding. As clearly shown in thedrawings, the shell member 21 and the inner end portion 8 of thehousing, together with the inner end of the core and wall 7, cooperateto form a part of the hermetically sealed envelope. Housing and core,together with closure plate 12, are fabricated from low reluctancemagnetic material, while shell member 21 and hermetic wall 7 arefabricated from non-magnetic material. The armature 17 is of coursefabricated from a magnetic material of a thickness and diameter suitableto form a low reluctance path across the inner end of the housing.

FiXedly secured centrally in the armature 17 is an axially extendingmetallic support rod 23, serving to support a multiplicity of axiallyaligned dielectric segments 24, 26, 27, 28, 29, 31 and 32. Thedielectric segments are preferably short tubular ceramic segmentsstacked one above the other in abutting relation as shown and secured inplace by a suitable nut 33 engaging the threaded free end of rod 23.Selected ones of the dielectric segments are provided with reduceddiameter portions seated within complementarily recessed portions inadjacent dielectric portions.

As clearly shown in FIGS. 1, 2 and 5, the armature and its attached,centrally disposed rod 23 are coaxially arranged with respect to theenvelope assembly 2, the rod or actuating stern extending substantiallyfrom one end of the envelope assembly to the other. The alternatedielectric and metallic envelope assembly 2 is preferably fabricatedfrom ceramic ring members 36 axially aligned and spaced one from theother, each being provided on its inner periphery with a re-entrantcylindrical flange portion 37 radially spaced inwardly from the innerperiphery of the ring. The re-entrant flange portions on the ceramicrings serve to prevent the formation of a continuous conductive pathbetween adjacent metallic portions of the envelope.

Each of the dielectric rings 36, is appropriately metalized on each ofits transverse surfaces, which surfaces are hermetically united as bybrazing to an associated metallic ring member 38, each metallic ringmember being provided with a radially inwardly extending flange portion39. Selected ones of the ring members 38 are additionally provided witha cylindrically extending flange 40 integral with the inner periphery ofthe radially extending flange 39. The radially inwardly extendingflanges 39 are hermetically brazed to the adjacent ceramic rings. Wheredesirable or necessary, suitable dielectric backing members 41 arebrazed to the opposite surface of radially inwardly extending flanges 39from the ring 36 to equalize stresses on opposite surf-aces of theflanges. As shown in the drawing, where the cylindrically extendingflange 40 is provided on the ring members 38, the flange is spacedradially inwardly an amount suificient to provide clearance between there-entrant flange 37 on ceramic member 36 and the cylindrical flange 40.This construction is shown in enlarged cross-section in FIG. 6.

To hermetically unite each sub-assembly comprised of one ceramic ring 36and two adjacent metallic rings 38 with adjacent envelopesub-assemblies, corresponding portions of ring members 38 extend towardeach other and are hermetically brazed to heavy metallic annular plates42, 43, 44, 46, 47, and 48, numbered consecutively from top to bottom asshown in FIGS. 1 and 2. In FIG. 5, since there are only three such heavyannular plates utilized, these plates are numbered consecutively 42, 43and 44. Each of the heavy contact flanges or plates is provided with aradially outwardly extending portion as shown in the drawings, and witha radially inwardly extending portion terminating at a central aperture51 in each of the plates.

In the embodiment of the relay illustrated in FIGS. 1 and 2, plates 43through 48 are provided with a centrally disposed coaxial metal shieldcylinder 52 pressfitted and brazed within the central aperture 51. Eachof the shield cylinders 52 closely surrounds the central actuating stem23.

In the embodiment of the relay illustrated in FIGS. 1, 2 and 5 each ofthe plates 42, 44 and 47 support a heavy cylindrical contact member 53having a longitudinal axis extending parallel to the axis of theenvelope and provided intermediate its ends with a groove in the natureof a transversely extending kerf providing a contact surface 54 and anabutment surface or stop 56. Each contact member is brazed in a suitableaperture formed in the associated contact flange at a point spaced fromthe central axis of the envelope. As shown best in FIG. 3, the remainingportion of contact 53 forming the bottom of the groove provides avertical abutment or surface 57 for purposes which will hereafter beexplained.

Comparing the relationship of contact members 53 in FIGS. 1 and 5, itwill be seen that in FIG. 1 the contact members 53 all extend in thesame direction, whereas in FIG. 5 the contact members extend in oppositedirections. Thus, in FIG. 5, the groove in contact 53 in the uppermostcontact illustrated is adjacent the lower end of the contact, whereas inthe lowermost contact 53 illustrated in FIG. 5 the groove is adjacentthe upper end of the contact. In FIG. 1 the grooves in contact members53 are oriented adjacent the lower end of the contact member as shown.

On each of plates 43, 46 and 48 in FIGS. 1 and 2, and on plate 43 inFIG. 5, a contact member 58 is provided brazed in a suitable apertureformed in the associated contact flange, and providing a contact surface59 lying in a plane coincident with the contact surface 54 on contactmember 53. Each of the contact members 58 is cylindrical about alongitudinal axis parallel to the axis of the adjacent contact member 53and the central axis of the envelope.

In the embodiment illustrated in FIG. 5, the contact flange 43 isprovided with a pair of such contact members 58, each extending onopposite sides of plate 43 so that corresponding surfaces 59 lie inparallel axially spaced planes also containing contact surfaces 54 ofassociated contact members 53. In this embodiment the plate 43 and itsassociated contact members 58 provide a common conductive pathassociated with each of the contact members 53 lying on opposite sidesof plate 43.

In order to complete an electrical circuit between the contact members53 and 58, a mobile contact assembly is provided comprising an annularmetallic member 61 sandwiched between one of the metallic envelope ringmembers 38 and a ceramic backing member 41, and provided with a radiallyinwardly extending resilient finger portion 62 having a heavy contactmember 63 of thick cross-section brazed on the free end of the finger62. A suitable baflle 64 is provided mounted adjacent the free end ofthe finger 62 in close proximity to the associated shield cylinder 52.The baffle plate 64 and shield cylinder 52 cooperate to preventvaporized contact material from migrating between the contact chambersassociated with the separate pairs of cooperating contact members 53 and58. This cooperative relationship is adapted to further isolate thecontact chambers from each other. This construction insures that therewill be no interference between each phase of a three phase circuit.

In the embodiment illustrated in FIG. 5, it will be noted that thebaffle plate 64 is omitted. The contact flange 43 in this embodimentfunctions to isolate separate pairs of contact members 53 and 58 fromeach other. Additionally, this embodiment is not a three-phase relay andseparation of the phases is therefore not critical. Both of theembodiments however utilize members of relatively large cross-sectionsuitable for interruptnig and carrying large currents in the order ofabout 200 amps. The heavy parts also function to draw heat from thecontact assembly, thus enabling a much higher current to be carriedcontinuously without generation of excessive heat.

In order to effect actuation of the relay, each of the movable andresilient contact fingers 62 is provided with an aperture through whicha reduced diameter portion of the associated dielectric stem segmentprojects. Adjacent segments thus trap the finger therebetween. It willthus be seen that movement of the armature by means of energization andde-energization of the solenoid will displace the resilient arm and thefloating contact thereon. The parts are preferably proportioned toprovide a resilient bow in the arm 62 in both of its positions. Such aresilient bow imposes a direct resilient closing force on the contacts,thus preventing or diminishing bounce due to impact shock or vibration.It will also be seen that the dielectric portion of the stem associatedwith each of the resilient contact arms 62 functions to electricallyinsulate the contacts from the longitudinally extending rod 23 which,like the magnetic assembly, is at ground poten tial.

The end of the envelope assembly opposite the magnetic solenoid assemblyis closed by the end cap assembly 4 as previously indicated, the end cap4 being provided with a cylindrically extending seal flange 66hermetically heliarc welded to the associated flange 38. The centralportion of the end cap assembly is provided with a dome 67 and asuitable tubulation 68 protected by a cap 69.

In order that the contact surfaces 54 and 59 may be properly aligned formating with the floating contact 63, assembly of the relay proceeds inwhat is believed to be a novel method. As will be seen from thefollowing description, adjustment of the cooperating contact surfaces isautomatically effected during the final braze operation.

It has been found that an economical and effective method to accomplishthis result is to pre-fabricate or pre-assemble separate sub-assembliesof the relay and braze the sub-assemblies in an initial braze operation,and subsequently hermetically join the composite subassemblies in afinal braze operation. In this manner separate sub-assemblies may befabricated and leak-checked before assembly into a completed unit. Oneof the first sub-assemblies to be assembled and brazed is the solenoidassembly 3, including housing 5, flange 16, wall 7, flange 9 and core 6.These elements are assembled with suitable jigs and braze rings andpassed through a brazing furnace so as to hermetically unite the membersone to the other to form a composite rigid and vibration freesub-assembly.

Another sub-assembly that is initially assembled and brazed is the endcap assembly 4, with a portion of protective cap 69 thereon, andtubulation 68 in open condition. The separate parts making up thissub-assembly are suitably brazed in a single operation. It will ofcourse be understood that appropriate brazing jigs are utilized tomaintain the parts in proper alignment.

A third sub-assembly that is pre-fabricated or preassembled andinitially brazed is the annular plate or contact ring 61 having theintegral radially extending finger 62 thereon, floating contact 63, andbafl le plate 64 brazed thereon. The contact ring 61 is convenientlystamped from .010" molybdenum sheet while the contact member 63 isfabricated from a thick piece of tungsten. Baflie plate 64 mayconveniently be fabricated from .005" molybdenum.

The separate sub-assemblies are assembled and the initial brazeoperation are conducted as follows: Referring to FIG. 1, metallicenvelope ring 21 is placed on a suitable jig having a center guide oralignment post of tungsten upon which are appropriately stacked inproper sequence the separate ceramic spacer members 24 through 32,respectively. Stacked on the radially inwardly extending flange 19 ofthe ring 21 is a ceramic ring 36, appropriately metalized. A braze ring(not shown) is interposed between the rings 21 and 36. Superposed onring 36 is metallic envelope ring 38 having radially inwardly extendingflange 39 adapted to be brazed to the adjacent metalized surface ofceramic ring 36. Seated within ring 38 on flange 39 is a backing member41, preferably of ceramic, also brazed to flange 39. Suitable brazerings are interposed between these members so that when the sub-assemblyis passed through the brazing furnace the parts will be hermeticallyunited. It will of course be understood that appropriate jigs surroundthese parts during the stacking operation to maintain them in axialalignment.

The heavy copper contact flange 48 is next stacked on the ring 38 so asto cause seating of the member 38 in an appropriate groove machined inthe contact flange 48. At this point it should be understood that allthe sub-assmblies are brazed at one time and that the flange 48 is notbrazed to the member 38 upon which it rests in this initial brazeoperation. The plate or flange 48 merely rests on the cylindrical member38, the groove in the flange 48 acting as a guide to coaxially align thecontact flange with the remaining elements of the combination. On theother hand, each of the contact flanges is brazed in this initialbrazing operation to the envelope ring 38 next above the contact flange.With the contact flange in place, a suitable jig is dropped into theaperture occupied by the contact member 59 in FIG. 1 to provide anabutment against which finger 62 may abut for proper alignment when thiselement of the combination is stacked. The assembly of the relayproceeds by sequential stacking of elements 41, 38 and 36 betweencontact flanges 48 and 47, and thereabove between succeeding pairs ofcontact flanges 47-46; 4644; 44-43; 43-42; and contact flange 42 andenvelope ring 38 next adjacent end cap assembly 4.

As the stacking progresses, appropriate jigs are inserted in theapertures in the contact flanges in place of the contact members 58 and53 which will ultimately be brazed in these apertures and which areshown in FIG. 1. Placement of these jigs is for purpose of ensuringproper positioning of the contacts with the resilient contact finger 62upon final braze. From the foregoing it will be apparent that eachcontact flange 42 through 48 forms the base for the next-above assemblyof metallic and ceramic rings, including backing rings 41, and each ofthese sub-assemblies is brazed in a single operation by passing, themultiplicity of stacked sub-assemblies through the brazing furnace atonce. Upon extraction of the stacked sub-assemblies from the furnace,each of the sub-assemblies in the stack will be united in a compositerigid unit, but the units will not be brazed to each other. At thispoint this composite sub-assembly may be leak-checked to make sure thatthe unit is vacuum tight. Sub-assemblies that are not vacuum tight arediscarded and replaced by tight subassemblies.

After the separate sub-assemblies are brazed into composite units, thesub-assemblies are hermetically brazed to each other in the followingmanner. Whereas stacking of the parts comprising each sub-assembly asexplained thus far proceeded from the end of the relay next adjacent thesolenoid assembly toward the end-cap assembly 4, stacking of theunitized sub-assemblies is accomplished in reverse order by invertingthe composite subassemblies and stacking them one upon the othercommencing with the sub-assembly including contact flange 42. As before,an appropriate jig having a center guide pin or post is provided uponwhich the sub-assemblies are stacked for final brazing.

In this operation one sub-assembly acts as a jig for the next superposedsub-assembly. After the first or lower-most composite sub-assembly isstacked on the jig in inverted position so that contact flange 42 formsthe uppermost element, contact member 53 is dropped into the aperture inthe contact flange adapted to receive it. The contact member istemporarily supported on the contact flange by placing a split springring of brazing wire about the contact member. Placement of the splitspring ring of brazing wire is gauged so that the grooved end of thecontact member extends above the contact flange an appropriate distance.

At this point, ceramic stem segment 32 is dropped over the center postor guide pin so that its reduced diameter end portion extends upwardly.The second composite subassembly including contact flange 43 is nowstacked on the first sub-assembly so that an end portion of cylindricalring member 38 indexes in the groove formed in contact plate 42. Thisensures coaxial alignment of the two subassemblies. It should be notedhowever that the second sub-assembly includes resilient contact arm 62,the free end of which must lie within the groove formed in contactmember 53. This requires that the two sub-assemblies be brought intoaxial alignment while the resilient contact arm is laterally offset fromthe contact member 53. This places floating contact plate 63 at theproper height so that subsequent rotation of the second sub-assemblyswings the floating contact into the groove in contact member 53.Rotation continues until the floating contact abuts the stop 57,whereupon it is turned in the opposite direction a small amount toprovide operating clearance between the edge of floating contact 63 andstop surface 57.

With the second sub-assembly in position as just described, a contactmember 58 is dropped through the aperture in contact flange 43 adaptedto receive it. The contact member 58 will pass downwardly until itscontact surface 59 rests on the floating contact 63. A split springbrazing ring is placed about the contact member 58 so that before thefinal braze operation it lies closely adjacent the upper surface ofcontact flange 43 when in inverted position,

As the stacking of the sub-assemblies progresses, the actuating stemceramic sections are also stacked about the center guide pin of the jigso as to appropriately engage the radially extending contact arm 62. Thelengths of the ceramic sections 24 through 32 making up the actuatingstem are proportioned so that upon final assembly and brazing, therelationship of each floating contact 63 with the associated contactmembers 53 and 58 is such that upon actuation of the relay to either amake or break position, the floating contact will be resiliently pressedagainst at least one abutment. Such resilient pressure is provided bygauging the travel of the solenoid and therefore the stern so thatovertravel is provided in either direction, thus producing a bow in theresilient arm 62 when the actuating stem is at either extremity of itstravel. It has been found that in a relay having the proportions of therelay illustrated a .020" overtravel will bow the resilient arm 62enough to cause resilient impingement of the floating contact withsuflicient force to withstand vibration to 10 G3 at 1000 cycles persecond.

After the sub-assemblies are all stacked and the resilient contact armsproperly oriented horizontally by appropriate rotation of eachsub-assembly, the floating contacts are oriented vertically withoutregard to contact surfaces 54 and 59 by placing the stacked ceramicsections 24 through 32 under compression so that the vertical height ofeach floating contact above the jig is fixed. It should be understoodthat at this stage of the assembly contact surfaces 54 and 59 on contactmembers 53 and 58 have not been oriented in a fixed relationship withrespect to the floating contact 63. It will be remembered that boththese contact members are temporarily supported on the associatedcontact flange by the split spring rings of brazing material.

The loosely stacked sub-assemblies are now ready for final braze, whichproceeds with the parts held in inverted position. Suitable brazematerial associated with each envelope ring 38 which loosely abuts anadjacent contact flange, upon melting, hermetically unites thesub-assemblies into a composite envelope portion 2. In the same brazeoperation the split spring brazing rings supporting contact members 53and 58 are melted, and upon melting release the contact members, whichsink downwardly until contact surfaces 54 and 59 rest on the floatingcontact. The braze material flows by capillary action between thecontact members and the associated contact flange to braze each contactmember rigidly in position. The contact surfaces 54 and 59 are nowproperly oriented with respect to each other and with respect to themobile or floating contact.

It will of course be apparent from the foregoing that the sequence ofassembly of the parts, and the sequence of brazing operations may bevaried to accord with different configurations. Thus, in the embodimentillustrated in FIG. 5, the lowermost contact members 53 and 58 arevertically oriented and brazed in one operation with the relay in anupright position as shown. Then the uppermost contact members arevertically oriented and brazed with the assembly inverted. Uponcompletion of the two braze operations each set of contact members isproperly oriented with the associated floating contact.

It has been found that this method of assembly materially increases thereliability of the relay in that substantially perfect orientation ofthe mating contact surfaces is obtained. This contributes tosimultaneous make or break as between a plurality of separate contactelements as in the two embodiments disclosed.

I claim:

1. In an electrical relay having an envelope portion comprised of aplurality of separate initially brazed composite sub-assembliesincluding a plurality of transversely extending contact flanges definingcontact chambers within each of which fixed contact members provide aplurality of spaced fixed contact surfaces in planar alignment adaptedto be simultaneously engaged and disengaged by a mobile contact, saidseparate initially brazed composite subassemblies being adapted to behermetically united in a final braze operation, the method of efifectingplanar alignment of the fixed contact surfaces in each contact chamberand cooperative correlation thereof with the contact surface of theassociated mobile contact comprising the steps of stacking saidsub-assemblies one upon another in association with braze materialpositioned so that the sub-assemblies are bonded one to the other whenthe braze material is raised to brazing temperature then cooled, fixingthe vertical position of each mobile contact with respect to a commonreference plane, releasably suspending the normally fixed contactmembers on said contact flanges in association with each mobile contactin a manner whereupon being heated to brazing temperature said normallyfixed contact members are released and sink into final position, heatingsaid stack of sub-assemblies to hermetically unite the sub-assembliesand effect release of 7 said normally fixed contacts, and cooling of theassembly to hermetically unite the sub-assemblies and braze the fixedcontact members when in final position to the associated contact flange.I

2. The method according to claim 1, wherein the heating of said stack ofsub-assemblies is effected While the stack is inverted in position.

3. The method according to claim 1, wherein said fixed contact membersare initially releasably suspended by means responsive to heat to effectrelease thereof, and after the application of heat said fixed contactmembers sink by gravity into abutting relation with the contact surfaceof the mobile contact.

4. The method according to claim 1, wherein said fixed contacts afterrelease are held by gravity in abutting relation with the contactsurface of the associated mobile contact While the stacked assembly iscooled to effect brazing of the fixed contacts to the contact flanges.

References Cited UNITED STATES PATENTS 2,886,668 5/1959 Steward et a1ZOO-144.2 2,886,671 5/1959 Steward et a1 200144.2 2,919,320 12/1959Edwards 29-155.5 X 3,057,047 10/ 1962 Zimmer.

3,137,061 6/1964 Lalak 29-203 JOHN F. CAMPBELL, Primary Examiner. J. C.CLINE, Assistant Examiner.

1. IN AN ELECTRICAL RELAY HAVING AN ENVELOPE PORTION COMPRISED OF APLURALITY OF SEPARATE INITIALLY BRAZED COMPOSITE SUB-ASSEMBLIESINCLUDING A PLURALITY OF TRANSVERSELY EXTENDING CONTACT FLANGES DEFININGCONTACT CHAMBERS WITHIN EACH OF WHICH FIXED CONTACT MEMBERS PROVIDE APLURALITY OF SPACED FIXED CONTACT SURFACES IN PLANAR ALIGNMENT ADAPTEDTO BE SIMULTANEOUSLY ENGAGED AND DISENGAGED BY A MOBILE CONTACT, SAIDSEPARATE INITIALLY BRAZED COMPOSITE SUBASSEMBLIES BEING ADAPTED TO BEHERMETICALLY UNITED IN A FINAL BRAZE OPERATION, THE METHOD OF EFFECTINGPLANAR ALIGNMENT OF THE FIXED CONTACT SURFACES IN EACH CONTACT CHAMBERAND COOPERATIVE CORRELATION THEREOF WITH THE CONTACT SURFACE OF THEASSOCIATED MOBILE CONTACT COMPRISING THE STEPS OF STACKING SAIDSUB-ASSEMBLIES ONE UPON ANOTHER IN ASSOCIATION WITH BRAZE MATERIALPOSITIONED SO THAT THE SUB-ASSEMBLIES ARE BONDED ONE TO THE OTHER WHENTHE BRAZE